Sulfonation of oils



May 8, 1962 U. B. BRAY SULFONATION OF OILS Filed Aug. 18. 1958 INVENTOR.

M' Aff/f,

ULF/c B. BRAY tat This invention relates to a process of makingsulfonates and particularly the preferentially oil soluble sulfonatesknown as mahogany sulfonates having molecular Weights in the range of400 to 900, generally about 450 to 600. More particularly, it relates tothe manufacture of such sulfonates by the suifonation of lubricatingoils from petroleum by the action of turning sulfuric acid (oleum) orsulfur trioxide.

The invention is illustrated by a drawing which shows, in FIGURE l, aschematic liow diagram of the process and in FIGURE 2, a mixing devicesuitable for use there- Suifonates of the type described above are ofgreat value in industry for making rust preventive and preservativeoils, for detergents in lubricating oils, particularly crank case oilsused in internal combustion engines, for control of surface tension,wetting and penetrating action of oils, as dispersants in fuel oils andfor many other uses. They are usually employed as sulfonates of sodium,ammonium, calcium or barium, altho numerous other metals can be used intheir composition, such as potassium, lithium, magnesium, iron,aluminum, lead, copper and zinc. Amine sulfonates are also important,such as those made with morpholine, ethylene diamine and dibutylamine.The mahogany sulfonates of the polyvalent metals are water insoluble andare preferred for antirust oils and lubricating oil compositions. Theycan be made in a basic form in which the metal is present in an amountexceeding the stoichiometric ratio.

Heretofore, in the manufacture of sulfonates from lubrieating oils, ithas generally been the practice to mix intimately the oil and oleum andsettle the product to remove a sludge layer which isl Withdrawn from thebottom of the settling tank after several hours. Owing to the relativelyhigh viscosity of the oil, which must be kept below about 125 F. toavoid decomposition of sultonic acids which are temperature sensitive,the removal of sludge has long been a serious problem. One method ofattacking the problem has involved diluting the sulfonated oil with ahydrocarbon solvent, generally a naphtha, to speed settling of sludgeand promote the transfer of the desired sulfonic acids from the sludgeinto the oil phase. However, if an aromatic naphtha such as toluene orXylene is used, it is necessary to iirst add water to preventsulfonation of the naphtha and formation of undesirable Water solublesulfonates. This method is described in my U.S. Patent 2,732,344. Whenparainic naphtha resistant to sulonation was used, it was found that theyield of sulfonate was seriously diminished, owing to the low solubilityof the sulfonic acids in parainic hydrocarbons. One of the chiefdisadvantages resulting from the use of water to facilitate theseparation of sludge from the suifonated oil is the dark color impartedto the sulfonate product and to the by-product lubricating oil. Inaddition to the dark red color of the lubricating oil, there is alsointroduced into the oil, undesirable carbonforming resins released fromthe sludge by the Water, considerably reducing its value as a motor oil.

My invention is not concerned, however, with themanufacture oflubricating oils by treatment of raw stocks containing unstable, sludgyhydrocarbons with sulfuric acid-usually 93-98%. The acid treatment ofsuch oils is long established in petroleum refining. The waste acidsludge resulting from it is a black tar containing little or nodesirable sulfonic acids of the oil soluble type.

I t t 3,033,898 Patented May si, 1962 In the sulfonation process, usingoleum having dis- ANALYSIS OF ACID PHAS To a 25 gram sample of acidphase, add 100 cc. water and 50 cc. of benzene; Heat'lthe mixture to.boilingy and add 20 cc. of a 15% NaCl solution to break the emulsion.Transfer to a separatingI funnel and' let stand 20 minutes to separate.Draw the bottom layer into' aA 250 cc. volumetricl flask, adjust volumevwith water and titrate the sulfuric acidi against StandardKGH` withphenolphthaleinindicator. Evaporate thev benzene' from the hydrocarbonsulfonate layer, heating in' an air stream until incipient decompositionas shown by odor of SO2 and weight the residue.

Calculation:-

25-Wt. of residue Using this method, the concentration of acid in theacid phase from treatment of.480 viscosity solvent treated neutral oil(v V.I.) with 1 0 vol. percent of oleu1n'-26% SOB-was 98.5%. AnotherYacid phase from sulfonation tested 93.11% H2804. These high'concentrations of spent acid illustrate the dilerenceV betweensulfonation of rened'oils and simple acid refining of raw oils forcolor.

I havenow' discovered that when a hydrocarbonl lubricating oil-stockY isused which is already pre-refined with sulfuric acid` and/or selectivesolvents and when oleum is employed as the sulfonating agent with SO'3concentrations trom- 15 to 25% and up to 65%, the acid remaining in thesludge is no longer a weak acid around Sil-80%, but has aconcentration'over 90% up to 100%. ln such a spent acid, I havediscovered that a major part of the desiredl sulfonic acids are soluble`while only a minor part remains in the oil-. Heretofore,`- whensulfonating suchoils, hydrocarbon or chlorinated hydrocarbon solventshave been used to'transfer the sulfonic acids from the acidphaseto theoil phase, or water-has been Percent H2SO4= X 100 added to release .thesulfonic acids ori the sultonation product has been allowed tostand formany hours` during which time oxidation. reactions proceeded with theformation of SO2 and H2O, thus liberating the mahogany acids from theacid phase. All such methods have been objectionable for one reason'l oranother, but principally because they resulted in products of poorVcolor and a lubricating oil with bad carbonization' properties. Longcontact time between the sulfonic acids-and the spent acid has resultedin oversulfonation with formation of more undesirable green acids.Dilution lwith water has transferred: color bodies and resins tothe'lubricating oil from which they can be'rem'oved only'with greatv dithcuty.

Because the acid phase from oleumsulfon'ations ofl rened lubricatingstocks usually separates into a thin', lower layer Yand a thick upper.layer Onstanding, many operators havev included in the upper lubricatingoil phase', av considerable amount of the thick sludgewhich is' rich insulfonic acids, thus confusing these' acids'with the truly oil solubleacids. l

I have now discovered that, while the' amount of' truly preferentiallyoil soluble sulfonic acids produced inl the reaction' between'pre-renned lubricating oils extracted desired sulfonates with solvents(e.g.: furfural, phenols, etc.) and oleum may be quite large-as much as25% of thestock with some oils-(l) only a minor portion of thesepreferred sulfonic acids is found Yin truesolution in the oil phase ofthe reaction mass of oleum and oil, and (2) the major portion of thesesulfonic acids (commonly called mahogany acids) is actually attached toor dissolved in the acid phase. This is distinctly contrary to theliteratureand the comomnly accepted belief that the oil soluble sulfonicacids (mahogany) are found in the oil theV oil insoluble acids (green)are found in the sludge. The reason for the contrary facts discovered byme appears to be that when sulfonating anpretreated stock which produceslittle or none of the ordinary tarry sludge when reacted withconcentrated sulfuric acid, the resulting droplets of acid phase from mysulfonation reaction contain sulfuric acid of higher S03 to H2O ratiothan formerly, and the droplets of acid phase are not loaded with tarryhydrocarbon polymers. This near absence or polymers in the acid phasedroplets appearsrto facilitate the attachment by absorption, adsorption,association and/or true solution of the mahogany acids in the aciddroplets to the point where, under my conditions of reaction, the oilphase cannot compete successfully for the socalled oil soluble sulfonicacids. Following this discovery, I have devised a process of separatingthe unsulfonated oil and refining it into a high quality lubricating,oil, while the are recovered mainly from the acid phase. y Y

It is an object of my invention to provide a process of making mahoganysulfonates without sacrifice in yield and, at the same time, make abyproduct lubricating oil of exceptionally light color and lowcarbonization number. Another object of my invention is to produce alight colored sulfonate of greater oil solubility and lower viscositythan heretofore produced. Other objects of the invention will becomeapparent from the following description. y

In carrying out my process, I prefer to charge a viscous lubricating oilfrom a Coloumbia, Venezuela, California, Mid-Continent, Coastal orArabian cruderoil, which has been solvent reiined to remove thepolynuclear aromatic hydrocarbons and resins. A mild sulfuric acidtreatment of the order of l to 50 lbs. 90-98% sulfuric acid per bbl. .ofdistillate can be usedV instead of or in addition to thesolventrefining. Reiined residual oils can also be used, such as a bright stockwhich has been de-resined with liquid propane and/or acid or solventtreated. Oils made-by `alkylation of benzene with long hydrocarbon sidechains, such as dinonyl naphthalene and high alkylates` produced asby-products in household detergent alkaneV manufacture, can also beemployed in my process. An oil having a viscosity in the range of about300 to more stages with intermediate cooling. Continuous mix- Ving andsulfonation of the oil and oleum is essential to .thesuccess of myprocess and, in order to obtain smooth, vuniform sulfonation with`arminimum of oxidativeY side reactions, I prefer to use a. high velocitymechanical mixer providing a high rate of shear, as will be furtherdescribed hereinafter.

After a shortreaction time of not more than 1 to Y20V minutes,the'sulfonation product is next separated by centrifugal action,employing a centrifugal force upwards of 1,000 times gravity (1000 G.)and usually in `the Yrange of 2,000 to 10,000 G. Under theV influence ofCII this force, the sludge particles are rapidly thrown from the oil toform an facid phase containing a major part of the mahogany sulfonicacids, excess sulfuric acid from the oleum, sulfurous acid (SO2),resins, tars, polymerization products and so-called green sulfonic acidsundesired in the mahogany sulfonate product. The lighter oil phase vfromthe centrifuge consists predominantly of unreacted hydrocarbonlubricating oil substantially `free of aromatics, carrying in solution avery small amount of mahogany sulfonic acids together with traces ofsulf'uricacid and SO2 held in solution largely by the mutualsolventaction of the sulfonic acids. In the preferred form of my invention, theoil phase is then neutralized with a monobasic alkali such as sodiumhydroxide or ammonia, and extracted with a suitable non-emulsifyingsolvent to recover the sulfonate, preferably in a multiple stage,countercurrent operation. The solvent is recovered, and the finishedoil, usually having a color less than l ASTM and carbonization numberless than 0.01 ASTM, is ready to be marketed as a high qualitylubricating oil.

Where it is desired to use the oil in heavy duty lubricant service, forexample, in gasoline and diesel engines, the oil phase can beneutralized directly with lime, barium hydroxide, or other polybasicmetal oxide, hydroxide or carbonate, then dehydrated and filtered. Theresulting oil needs no purification because of its low sulfate content,a typical sample assaying 0.043% Na2SO4 equivalent. The sulfonatecontent, expressed as sodium sulfonate, may be in the range of 2 to 5percent.

When the sulfonate is extracted from the oil phase, it can be washedwith water and an emulsion-breaking solvent, then dehydrated to providea product of exceptionally light color, usually about l-2 ASTM at 0.9%ash concentration in oil and low viscosity, adapting it to special uses.However, I usually prefer to combine it with thersulfonate derived fromthe acid phase, as will be described hereinafter.

In processing the acid phase from the centrifuge, I have discovered thatthe mahogany sulfonic acids can be selectively extracted with aparallinic hydrocarbon boiling in the range of 200 to 400 F., hereincalled a parainic naphtha. The undesired color bodies are allowed toremain largely with the acid phase in chemical combination with thestrong acid. However, the yield of mahogany acid obtained is low unlessinordinately large volumes, eg., 5-10 volumes, of naphtha are used.

y I have discovered that the addition of a small amount of Water to theacid phase greatly increases the yield of mahogany acids, but thatdirect contact with Water must `be avoided or an excessively darkcolored product will result. I have discovered that if the acid phase isfirst diluted with at least an equal volume of volatile parainicnaphtha, water can be introduced in an amount of about 3 to 12% of thevolume of the acid phase, Without excessive hydrolysis of the complexcompounds of acid and color bodies and that a selective release of themahogany acids is obtained. A high speed mechanical mixer providing ahigh rate of shear is desirable for the mixing operation, the mixershown in FIGURE 2 being suitable. Naphtha suitable for this purposeshould contain less than 2% aromatic hydrocarbons and preferably less,than 1% to avoid contamination by sulfonation of aromatics in thenaphtha. A suitable diluent is V.M. & P. (varnish makers and painters)naphtha boiling inthe range of 250-280 F.Y and free of aromatichydrocarbons. A parainic extraction naphtha boiling at 290-325 F.

Vwhich has been treated with concentrated sulfuric acid and redistilledis also suitable.

The naphtha solution of the released sulfonic `acids is then separatedfrom the sulfuric acid and sludge and neutralized with an alkali orammonia. Removal of the paraiiinic solvent by distillation leaves thecrude sulfonate in concentrated form usually about 50 to 60% in oil.InasmuchY as mahogany sulfonates of this concentration are semi solidsand diicult to handle, I prefer to dilute them with a light lubricatingoil which may be the. byproduct oil produced in the process or anotherlubricating oil distillate, for example, a pale oil, sufficient diluentoil being added to reduce the sulfonate content to about 30 to 40%. Thecrude sulfonate is then purified with water and emulsion breakingsolvent, preferably after combining with the sulfonates extracted fromthe oil phase. Afterv recovering the emulsion breaking solvent bydistillation from the concentrated sulfonate-oilA solution, it isdehydrated and filtered hot for the market or it can be converted topoly-valent metal sulfonate while still in solution in the emulsionbreaking solvent as described in my U.S. Patent 2,689,221. My processwill be more fully understood by the following description thereof inconjunction with the drawing.

Referring to the drawing, hydrocarbon oil from tank is conducted by line11 through cooler 12 to mixer 13, where it is mixed intimately with astream of oleum supplied from tank 14 vby line 15. The mixer 13 consistsof any eficient mixing machine such as the well known Stratco mixer or ahigh speed centrifugal pump whichV is throttled down or recycled. Iprefer to use the geartype pump such as the Viking or Roper pump inwhich meshed gears run together and wipe acid against the housingef thepump in intimate contact with the oil, giving a strong churning action.The mixing action of the pump is enhanced by throttling the inlet bymeans of valves 16 and 17. For example, using a pump with capacity of 50gallons per minute, I may throttle the feed to the pump to providea flowrate of only 10 to 20 gallons per minute. The result of this method ofoperation is that the pump rotor is operating in a partial vacuum,usually about 10 to 2O inches, mercury, and the acid and oil. arechurned into a line, intimate suspension providing uniformity ofreaction.

Cooler 12 is valuable in warm weather to keep the temperature of the oilfeed within the desired range, usually about 50 to 70 F. 'Ihe amount ofoleum mixed with the oil in mixer 13 is controlled to give aytemperature rise of about 20 to 30 F., thereby avoidingover-sulfonation.

From mixer 13 the oil-acid mixture passes by line 18 through cooler 19,and thence to mixer 20 where the mixing operation is repeated,additional oleum being introduced through valve 21. A diagramof therotary gear pump typical of the mixer I have used successfullyis shownin FIGURE 2. Using this mixer, it is desirable to introduce the oleuminto the oil close to the inlet of the pump and, if desired, the oleumcan be introduced through -a nozzle, extending directly into the pumpchamber, as shown at 22.

Referring again to FIGURE 1, the mixture of oil and oleumV is passed byline 23 to pump 24, suitably of the centrifugal type, and thence to thecentrifugal machine 25 where it is separated into an oil phase leavingby line 26 and a heavier acid phase leaving the centrifuge by line 27.If desired, additional reaction time can be obtained before separatingthe phases by recyclingthe oil through reaction drum 2S and back throughmanifold 29 to pump 24. Any desired reaction time' can be obtained byregulating the level and consequently the hold-up, in drum 28. Whenoperating in this manner, it is desirable to close valve 30 and openvalve 31 in transfer line 32.

The oil phase in line 26 carrying a portion of the desired sulfonicacids in solution is next neutralized with caustic alkali from supplytank 3:3 from which it is drawn by valved line 34, the neutralizationtaking place in mixer 35, whence the oil ows to horizontal settling drumS6. The caustic solution. in tank 433 may suitably be a 20% solution ofsodium hydroxide or other base. of a monovalent cation. Potassiumhydroxide, lithium hydroxide, or ammonium hydroxide can also be used,but sodium hydroxide is preferred because of its low cost and ease ofrecovery in the subsequent extraction steps.

In order to facilitate the removal of sodium sulfonates from the oil, anemulsion-breaking solvent is introduced by line 42 and by recycle line37. This solvent is suitably a four-carbon alcohol such as secondarybutyl alcohol; Other solvents for this purpose are described in mypreviously issued U.S. Patents, 2,453,690; 2,689,221; 2,746,- 987;2,732,344 and 2,824,126. In settler 36, a brine layer consisting largelyof excess alkali, water and solvent, and sodium salts of sulfur acids`is withdrawn by line 38. An intermediate layer comprised largely ofsulfonie soaps is withdrawn by line 39 while an upper layer of oil isconducted by line 40 to mixer 41 wherein it is thoroughly mixed withkadditional solvent introduced by line 42 and with water introduced byline 43. The ratio of solvent to water and oilv in mixer 41iscontro'lled to brin-g about a. second separation into th-ree phases, abrine phase discarded by line 44, an intermediate" solventphasecontaining most of the remaining sulfonateswithdrawn by line 45,and an oil phase withdrawn by line y46. The-solvent phase containingusually only 1r to 5% of sulfonate in solution is recycled to mixer '35by line'37', ashereinabove described.

The extracted oil phase, containing solvent and some water is nextconducted by pump 4'7 to'heater 48,r shown here as a pipe heater, andthence to stripping tower 49 where the solvent is `flashed off andstripped with steam introduced at 50. Solvent vaporsare condensed incooler 51 and the solvent then" passes by lines 52 and 5-3 to solventstorage tank 54. The oil which may be at a temperature of about 300 to400 F., iloWs by line 55 to-ashdrum 56, preferably of the vacuum type,to remove dissolved water, and the lubricating oil product thenr passesout of the system by valved line 57 leading to tank 58. If desired, thesmall: amount of sodium sulfonate remaining in the oil-less than0.1%-can be converted to polyvalent' metal sulfonate such as calcium orbarium; by contacting with the appropriate salt of such metal as is wellknown' in the art.

RECOVERY or sULEoNArE FROM THE AC1-D PHASE i The acid phase withdrawnfrom centrifuge 25 by line Z7, which may constitute about 25 to 65% byvolume of the mixture ofr oil andacid charged to the; centrifuge, isconductedk to mixer 60 'where' it is thoroughly diluted with about 1 to3 volumes of a paralinic hydrocarbon diluent Iwithdrawn from tank 61 byline'62. The mixture then passes by line 63 to a second mixer, 64,Iwhere it is intimately contacted with a stream of Water introduced byline 65. Instead of water, however, I may use an aqueous sulfuric acid,generally of about30-to 75%v concentration. The purpose of the water orthe aqueous acid is to release from the acid phase the desirablesulfonic acids which are heldin solution by the highly concentratedsulfuric acid.v The action involves hydrolysis of complex compoundsformed between. the strong sulfuric acid and the sulfonic acids. Thereare also present in the acid phase, complex compounds of resinous andhighly coloredV polymerization products in combination with strongVacid, and it is very desirable that these compounds be allowed to remaininthe acid phase undisturbedkand: unhydrolyzed in order to avoidcontamination of the sulfonate product with thesecolor bodies.- I` havediscovered that if the water or diluted sulfuric acid introduced by line65 is intimately and rapidly mixed with the diluted acid phase fromvmixer 60, hydrolysis of the color complexes can be greatly diminished.To achieve selective hydrolysis of Vsulfonic acids and their releasefrom the. acid phase Without, at the same time releasing undesired colorbodies,V I have found it necessaryk to first. mix the acid phase withatleast an equal volume of the hydrocarbon diIuent. To obtain rapid andintimate contact between the water or dilute sulfuric acid and the acidphase, I prefer to use a mixer of the type showny in FIGURE 2, theWater, in this case, being introduced by nozzle 22. The amount of waterneeded toV release the sulfonic acids is about l to 4% of theV oilcharged to the system byline 11, equivalent .to about 3 to 12% of the'acid phase in line 27. Less water can beV used with higher naphthadilutions. When using diluted Y,sulfuric acid for this purpose insteadof water, it is necessary to increase the amount of dilution stillfurther.

From mixer 64, the acid phase and diluent hydrocarbon' as l50'neutra1oil, pale Oil of 60 to 200 SSU viscosity at 100 F., and the like.

From mixer 69,V an alkali brine containing excess caustic and salts ofsulfur acids is settled in settler 72 and withdrawn by line 73. Thehydrocarbon diluent solution of sulfonate is conducted by line 74 topipe heater 75 and thence to stripper 76 where the hydrocarbon dilnentis driven overhead and condensed in 'cooler 77, whence it owsrby line 78back to diluent Vtank 61. Stripped soaps from 76 ilow by line 79 throughcooler 80 into mixer 81 where they are thoroughly mixed with solventintroduced by line 82 and water, if necessary, by line 83. Sodiumchloride brine from tank 84 may also be needed to assist in thepurication of the sulfonic soaps. The mixture then passes to settler 85where brine is removed by line '86, and the purified 'sulfonate-oilstream passes by line 87 to pipe heater 88 and liash drum 89 to removewater and solvent vapors which are condensed in cooler 90, recoveredsolvent flowing by line 91 and pump 92 back to mixer 81 or, if in excessof that needed there, by line 53 to solvent storage S4. r[he strippedoil-soap product now passes by line 93 to vacuum shipper 94 wherertheremainingidissolved watervis removed at a temperature of about'300" F.,the dehydrated soap being withdrawn yfrom the system by pump 9S and line96 leading to tank 97. u Y

Sulfonic soaps extracted from Ythe oil phase in'settler 36 Yandwithdrawn by line 39 can be separately puried and dehydrated by asuitable solvent treatment, as indicated hereinabove, but I prefer tointroduce them into mixer 81 where they are combined with the soaps fromthe acid phase and puriiied simultaneously. Irhave found that thecombined sulfonates from the two phases separated in centrifuge 25V aresomewhat ,diiferent in respect toroil solubility and emulsion formingcharacteristics, and that, when combined, theV purification operation isgreatly facilitated.

The data presented in the following `examples further illustrate theinvention.V They were obtained in the sul-Y fonation of a 480 neutraloilV with oleum containing 267% S03. The oil was a solvent renedlubricating distillate having a viscosity index of 90 and viscosity of500 SSU at 100 F. The sulfuric acid absorption test (ASTM D-484-52)Yshowed 87%'acid insoluble. In sulfonating this oil, the oleum wasapplied thru the mixer shown in FIG. 2, employing two mixers in serieswith intervening cooling to 80 F. A rise in temperature Vof Y 30 F.occurred in the irst stage starting with a stock temperature of 64 F.,with a rise of 20 F. in the secondstage, the oleum requirement being9.5% by volume for the complete treatment. Y

The mixing pumps in both stages had a capacity of 90 gallons per minuteoperating at a rotational Aspeed of 260 r.p.m. and the oil feed wasthrottled down to a flow rate of 30 gal. per min. providing a vacuum inthe mixer of 20-24 inches mercury.Y

From the second contacter, the reaction mixture was passed thru a coolerrequiring less than tenV minutes for cooling, usually about six minutesor less, then to the centrifugal separator. l may pass the reactionproduct directlyrfrom the -contactor to the centrifuge without coolingor further mixing, thereby reducing the time interval between mixer andcentrifuge to only about l0 to 60seconds. Centrifugal separation ofsludge was effected in a De Laval machine with the centrifuge bowl-4.5in. diamrotating at 12,700 r.p.m. producing a centrifugal force ofapproximately 9,000 times gravity. The following example shows theeffect of feed rate 0n vvalue of 451.

sludge Vseparation at ambient temperature, F.:

Example 1 Residence, Oil Phase, Acid Phase Feed Rate, gals/hr. Time,Percent Percent Mins.

9. 2 64. 6 35. 4 4. (i4. 3 35. '7 3. o c4. 0 36. o 2. 24 55. 0 45. 0 2.05l. l 48. Q 0. 75 l5. 1 84. 9

follows 0.93%Y (as casoi).

Ash

Sodium sulfonate 6.52%. Color, ASTM Less than l. Alkali value 0.3.

Sulfate as Na2SO4 043%.

. T itration of the acid phase 4from run 2 showed an acid Extractionwith 250% by wt. of paraffinic solvent (VM&P) in three stages, 100, and50, gave a combined extract having an acid value of 59, the 3rd extracthaving an acid value of only 3.9, showing nearly complete recovery ofsulfonic acid -from the acid phase Without addition of water to releasethe sulfonic acids.

q The combined extract was neutralized with an excess of sodiumhydroxide solution, ibrine was settled and diS- carded. The solvent wasdistilled off and the sulfonate was dehydrated to yield 63 parts byweight of crude sulfonate. This was purified by mixing with 62.5 partsof aqueous sec. butanol and 62.5 gm. sodium chloride brine 2.5%. Brinewas settled out and the purified sulfonate was dehydrated to 350or F.The yield was 62.5% based on the weight of the acid phase.

Analysis:

Ash, as NaSO4 7.54. Alkali value 0.1. Sulfate, as Na2SO4 0.58%.Sulfonate (calc.) 53.3%. Color, ASTM 4.5-5 (diluted).

Example 2 was 38% of the sulfonated mixture. The acid phase was 9 mixedwith an equal volume of paraiinic naphtha free of aromatics, thenYdivided into two equal parts which were treated as follows:

Part 1 Part 2 2% water mixed in.

Settled 15 min.-A.V.-26.2. Settled 30 min.-A.V.-25.1 Settled 60min.-A.V.23.5. Sludge layer,1 28.2%, AV-857. Sludge layer discarded. Oillayer neutralized-NaOH. Brine settled out-discarded. Solvent stript withsteam. Yield-Crude soap 142.8%. Purified-aqueous sec. butanol.

4% water mixed in.

Settled 15 min.-A.V.24.1. Settled 30 min.-A.V.-21.5. Settled 60min.-A.V.-20.5. Sludge layer,1 25.5%, AV-795. Sludge layer discarded.

Oil layer neutralized-NaOH. Brine settled out-discarded. Solvent striptwith steam. Yield-Crude soap 1-43.3%. Purified-aqueous sec. butanol.

Dehydrated to 350 F Dehydrated 150350 F. Yield 38.7%. Yield 39.3%.y

Analysis: Analysis:

Ash-8.65%. Ash-8.83%. Alkali value 2.8.. Alkali value 3.4. Sulfate0.332%. Sulfate 0.275. Yield 118.15%. Yield 1 18.82.

1 Percent by weight based on the weight of the acid phase.

100 parts of the oil phase were neutralized with NaOH, washed andextracted with -aqueous sec. butanol, then dehydrated to yield 8.5% ofsodium sulfonate having an ash value of 10.42%. The extractedlubricating oil was nearly lfree of sulfonate as shown by the 10W ashvalue of 013%. The yield of oil was 89.8% ofthe oil phase by 4weight andthe color was pale yellow, less than 1 ASTM.

Example 3 Another sulfonationk was made as above described and themixture was separated on the centrifuge immediately, collecting 6gallons of oil phase and 2.3 gallons of acid phase. The oil phase wasneutralized with excess NaOH solution at 160 F. and extracted with 1/2volume of aqueous secondary butanol (28%- H20). Brine and sulfonatelayers were Iremoved. It was again washed with a mixture of 10% byvolume of aqueous secondary butanol and 20% of water at 160 F. Thealcohol layer was withdrawn and the oil was dehydrated to 350 F.

Yield `87 .5 Analysis of the oil follows:

AAsh 009%.

Alkali value Neutral to phenolphthalein. Sulfate as NazSO.; .002%.Carbon residue, ASTM 0.00. Color, ASTM Below 1. Flash 480 F. Gravity,API 30.0. Viscosity, SSU/210 F 58.53. Viscosity index 96.28.

The sulfonate extract from the above oil was dehydrated to 350 F. Yield,1218 grams. For convenience in handling, viscosity was reduced by adding200 gm. oil, the resulting mixture testing as follows:

Ash Percent-- 8.89 Sulfonate do 56.8 Alkali value 3.9 Sulfate Percent0.16 Viscosity at 210 F. SSU 22.0

This viscosity is low ifor a sulfonate-oil solution having a sulfonatecontent of 56.8% (calculated from the neutral ash value and molecularweight of the calcium sulfonate, 480).

The acid phase from abovev was diluted with 3 vol- 10? urnes ofnon-arornatic naphtha and twok samples were treated as lfollows:

Samnln I, 1I

Volumn, no 300 300 Weight, gms 265 265 Solvent naphtha a ed, c 900 900Water added, gms 18 H2SO4-75%, added, gms. 60 Mixed and settled 30mins.;

Acid value ol oil layer'. 20. 2 28.0 Settled 1 hour, acid value 18. 6.25. 6 Settled overnight, acid value-- 17. 8 23. 2 Thin sludge (HrSOr),cc.. 66 108 Thick sludge, cc 10 NaOH-20%, added, cc.- 55 71 Alkali valueof wet sulfonate..` 3. 4 3. 8

15 Dehydrated at 350 F. Yield, gm 157 152 Ash 7; 59 7. 65 Alkali valueO. 5 0. 1 Sulfate, as NaiSOr 0.391 0. 440

This experiment shows that theV additonof 60 gramsV of 75% sulfuric acidhas about the same effect in driving the sulfonic acids into thenaphthawsolution as does 18 grams of water. X

EXAMPLE 4 Volumn of Y Neutral, l Gravity, Test Oil phase, Acid Value AshPer'- API Percent cent It willbe noted that the increased yield of oilphase in test2 is' the result of inclusion of a larger amount oftheacidA phase therein, as shown by the higher acid value and lower APIgravity, as well as the increased ash after neutralization with sodiumhydroxide.

As an indication of the suitability of a lubricating oil stock for myprocess, I can use the sulfuric acid absorption test, ASTM De484-52,referred to hereinabove. By this test, a sample of the oil is extractedwith 95% sulfuric acid and the volume of` the unabsorbed oil ismeasured. Gils with an acid absorption number of between V andll00 aresuitable, preferably between 85 and 100. A very good oil from Californiacrude which I have used extensively has an acid absorption number of 94.

The severity of the sulfonation treatment employed in my process willvary with the character of the oil treated, particularly its aromaticcontent. Most oils require about 10 to 15 percent by weight of oleum of25% S03 content. Based on S03, this is equal to 2.5 to 3.7%. Oilshigh inaromatics, such as synthetic alkyl benzenes, may require up to 10% S03whereas some petroleum stocks can be fully sulfonated with only 2% S03used in the form of oleum of l0 to 65% S03 content. In this specicationand claims, the term oleum is used to mean an acid of this strength.Also, where it is specied the sulfonation mixture be separatedimmediately by centrifugal action, a reasonable time for transferringthe oil must be allowed, usually from 1 to 10 minutes, not more than 1hour.

Having thus described my invention, what I claim is:

1. The process of making mahogany sulfonates which comprises contactinga hydrocarbon lubricating oil having an acid absorption value between 80and 100 with oleum of 10 to 65% S03 content, to produce a mixture ofmahogany sulfonic acids, green sulfonic acids, sulfuric and sulfurousacids and tars, then immediately, without diluting the said reactionmixture, separating it into an oil phase and an acid phase bycentrifugal force before decomposition of said sulionic acids and tarsoccurs to contaminate the mixture with oil soluble color bodies,diluting said acid phase with from 1 to 3 volumes of a paratlinicnaphtha solvent, thereby forming a solution of sulfonic acids in saidnaphtha solvent, separating an acidsludge, neutralizing the sulfonic.acids in both said naphtha solution and said oil phase by contactingwith a base of a monovalentcation and recovering theV resulting mahoganysulfonates therefrom.

2. The process of claim 1 wherein the mahogany sulfonate'from the oilphase consisting predominately of oil is combined with the mahoganysulfonate obtained from the acid phase and the mixture of oil andsulfonates is puriiiedof contaminating salts of sulfur acids and greensulfonic acids by extraction with'gwater'and an emulsion breakingsolvent.

3. The process of claim 1 wherein the transfer of mahogany sulfonicacidsfrom said acid phase` to said naphtha solvent is facilitated` byintroducing into the diluted acid phase from 3 to 12 percent of waterbased on the. volume of said phase, and intimately mixing it therewithafter said dilution step and before separating said acid sludge.

4. The process of claim l wherein the transfer of mahogany sulfonicacids from said acid phase to said naphtha solvent is facilitated byintroducing into the diluted acid phase, a solution of sulfuric acid andWater in a concentration of about 3075%, and intimately mixing it withsaid diluted acid phase afterV said dilution step andbefore separatingsaid sludge, the amount of sulfuric acidV added being sufficient toreduce the acidity of said sludge to less than 900 mg. KOH per gm.equivalent when titrated with phenolphthalein indicator. v I

5. The process of claim 1 wherein the centrifugal force employed is atleast 1000 times gravity.

6. The process of cl' 1 wherein the one to ten minutes.

7. The process of making petroleum mahoganysulfonates comprisingintimately mixing a lubrication oil hav- Y ing an acid absorption valuebetween 80 and 100 and a Y Vsulfonating agentV comprising oleum of l to65% S03 separation of said Y oil phase and said acid phase iscompletedwithin about said acid phase with at leastV an equal volume of avolatile paraftinic hydrocarbon diluent, intimately'mixing the resultingdilution with about 3 to 12% of water based on the volume of said acidphase, thereby forming a solution of sulfonic acids in said paraiiinichydrocarbon diluent and an acid sludge, separating said sludge,neutralizing said sulfonic acids with an alkali thereby forming aneutral sulfonate in solution in said hydrocarbon diluent, evaporatingsaid diluent and subjecting'the neutral sulfonate to the action of waterand an emulsion preventing solvent to remove therefrom undesirableYsalts of sulfur acids and green acid sulfonates.

8. The process of claim 7 wherein the amount of oleum employed issufficient to provide said sulfonation step with 2 to 10% S03, based' onthe weight of oil treated.

9. The process of making mahogany sulfonates by sul` fonation oflubricating oil which comprises contacting a partially reiinedhydrocarbon oil of about 350 to 800l molecular weight from whichpolynuclear aromatics and` unsaturates have been removed, said oilhaving an acid absorption value between and 100 comprising contactingsaid oil with oleum of l0 to 65 S03 content, employing suiicient oleumto produce a mixture of sulfonic acids, unsulfonated oil and spentsulfuric acid in which the spent acid has a concentration of about to100% H2504 oil-free basis as a result of which a majorproportion of thedesired mahogany acids are retained in the acid as an oil-insolublecomplex, diicult to separate from said unsulfonatedoil, subjecting themixture to the action of centrifugal force greater thanV 1,000 timesgravity, thereby separating said unsulfonated oil having a minor amountof mahogany sulfonic acids from said spent acid by'extraction with aboutl-3 volumes of a hydrocarbon solvent, ,neutralizing the mahoganyacid-solvent extract and distilling the solvent from the resultingmahogany sulfonate. Y Y

2,406,763 Griesinger Sept. 3, 1946 `2,479,202 Bransky et al. p Aug. 16,1949 2,732,344 Y Bray Jan. 24, 1956 l OTHER REFERENCES Brown: Instituteof Petroleum Review, vol. 9, pages 314-321, 1955.

1. THE PROCESS OF MAKING MAHOGANY SULFONATES WHICH COMPRISES CONTACTINGA HYDROCARBON LUBRICATING OIL HAVING AN ACID ABSORPTION VALUE BETWEEN 80AND 100 WITH OLEUM OF 10 TO 65% SO3 CONTENT, TO PRODUCE A MIXTURE OFMAHOGANY SULFONIC ACIDS, GREEN SULFONIC ACIDS, SULFURIC AND SULFUROUSACIDS AND TARS, THEN IMMEDIATELY, WITHOUT DILUTING THE SAID REACTIONMIXTURE, SEPARATING IT INTO AN OIL PHASE AND AN ACID PHASE BYCENTRIFUGAL FORCE BEFORE DECOMPOSITION OF SAID SULFONIC ACIDS AND TARSOCCURS TO CONTAMINATE THE MIXTURE WITH OIL SOLUBLE COLOR BODIES DILUTINGSAID ACID PHASE WITH FROM 1 TO 3 VOLUMES OF A PARAFFINIC NAPHTHASOLVENT, THEREBY FORMING A SOLUTION OF SULFONIC ACIDS IN SAID NAPHTHASOLVENT, SEPARATING AN ACID SLUDGE, NEUTRALIZING THE SULFONIC ACIDS INBOTH SAID NAPHTHA SOLUTION AND SAID OIL PHASE BY CONTATING WITH A BASEOF A MONOVALENT CATION AND REMOVING THE RESULTING MAHOGANY SULFONATESTHEREFROM.